Electron Energy Interplay in the Geomagnetic Trap Below the Auroral Acceleration Region

Abstract

This publication addresses the collisional superthermal electron dynamics below the auroral acceleration region (AAR). This region is the portion of an auroral field line with a field aligned electric field that leads to the formation of precipitating monoenergetic keV electron fluxes that produce the discrete auroral displays observable from the ground. It is assumed that these precipitating electron fluxes are monoenergetic and accelerated through a potential drop, V, such that these electrons are peaked at an energy E₀ = eV, where e is the electron charge. Monoenergetic electrons precipitating into the upper atmosphere degrade to lower energies via many different collisional processes and produce the secondary electron population with energies of 10-100s eV which escapes back to magnetospheric altitudes and becomes geomagnetically trapped between the AAR and the upper ionosphere. The secondary electrons in this geomagnetic trap transfer energy via elastic Coulomb collisions to the thermal electrons. That energy is then returned to the topside ionosphere as heat flux carried by the electron thermal conduction which is essential to maintaining the topside electron temperature.